package api

import (
	"bytes"
	"encoding/json"
	"io"
	"net/http"
	"regexp"
	"strings"
	"time"
)

var releaseBuilderTagPattern = regexp.MustCompile(`^v\d+\.\d+\.\d+$`)

type releaseBuilderRequest struct {
	Tag       string `json:"tag"`
	Notes     string `json:"notes"`
	Mandatory bool   `json:"mandatory"`
}

func (s *Server) handleAdminReleaseBuilderStatus(w http.ResponseWriter, r *http.Request) {
	s.relayReleaseBuilder(w, r, http.MethodGet, "/v1/status", nil)
}

func (s *Server) handleAdminReleaseBuilderStart(w http.ResponseWriter, r *http.Request) {
	r.Body = http.MaxBytesReader(w, r.Body, 16<<10)
	var request releaseBuilderRequest
	decoder := json.NewDecoder(r.Body)
	decoder.DisallowUnknownFields()
	if err := decoder.Decode(&request); err != nil {
		writeError(w, http.StatusBadRequest, "invalid release request")
		return
	}
	request.Tag = strings.TrimSpace(request.Tag)
	request.Notes = strings.TrimSpace(request.Notes)
	if request.Tag != "" && !releaseBuilderTagPattern.MatchString(request.Tag) {
		writeError(w, http.StatusBadRequest, "tag must be blank or look like v0.2.64")
		return
	}
	if len(request.Notes) > 4000 {
		writeError(w, http.StatusBadRequest, "release notes are too long")
		return
	}
	body, err := json.Marshal(request)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "could not prepare release request")
		return
	}
	s.relayReleaseBuilder(w, r, http.MethodPost, "/v1/releases", body)
}

func (s *Server) relayReleaseBuilder(w http.ResponseWriter, incoming *http.Request, method, path string, body []byte) {
	if s.cfg.ReleaseBuilderURL == "" || s.cfg.ReleasePublishToken == "" {
		writeError(w, http.StatusServiceUnavailable, "the Docker release builder is not configured")
		return
	}
	request, err := http.NewRequestWithContext(incoming.Context(), method,
		s.cfg.ReleaseBuilderURL+path, bytes.NewReader(body))
	if err != nil {
		writeError(w, http.StatusInternalServerError, "could not prepare builder request")
		return
	}
	request.Header.Set("Authorization", "Bearer "+s.cfg.ReleasePublishToken)
	if len(body) > 0 {
		request.Header.Set("Content-Type", "application/json")
	}
	client := &http.Client{Timeout: 10 * time.Second}
	response, err := client.Do(request)
	if err != nil {
		writeError(w, http.StatusServiceUnavailable, "the Docker release builder is not available")
		return
	}
	defer response.Body.Close()
	payload, err := io.ReadAll(io.LimitReader(response.Body, 1<<20))
	if err != nil {
		writeError(w, http.StatusBadGateway, "could not read the Docker release builder response")
		return
	}
	w.Header().Set("Content-Type", "application/json")
	w.Header().Set("Cache-Control", "no-store")
	w.WriteHeader(response.StatusCode)
	_, _ = w.Write(payload)
}